Optical sighting device having re



SEARGHFQ Dec. 28, 1948.

E. H. GOLDSMITH ET AL 2,457,543 OPTICAL SIGHTING DEVICE HAVING REFLECTOR MEANS FOR TRACKING MOVABLE OBJECTS 6 Sheets-Sheet 1 Filed March 16, 1946 FIG.

E. H. GOLDSMITH //vl//vr0/; s; J m SCHAEFER R. v TERRY By L Q X 7% M ATTORNEY Dec. 28, 1948. E. H GOLDSMITH ET AL 2,457,543

OPTICAL SIGHTING DEVICE HAVING REFLECTOR MEANS FOR TRACKING MOVABLE OBJECTS Filed March 16, 1946 6 Sheets-Sheet 2 E. H. GOLDSMITH INVENTOR5-' J. W SCHAEFER R. M TERRY 5y /flmg; W SZA A TTORNEY Dec. 28, 1948. E. H. GOLDSMITH ET AL 2,457,543

OPTICAL SIGHTING DEVICE HAVING REFLECTOR MEANS FOR TRACKING MOVABLE OBJECTS Filed March 16, 1946 6 Sheets-Sheet 3 FIG. 3

FIG. 5

E. H. GOLDSMITH J. W SCHAEFER lNVENTO/QS V TERRY A TTOPA/EY 1948. E. H. GOLDSMITH ET AL 2,457,543

OPTICAL SIGHTING DEVICE HAVING REFLECTOR MEANS FOR TRACKING MOVABLE OBJECTS Filed March 16, 1946 6 Sheets-Sheet 4 FIG. 4.

ATTORNE V Dec. 28, 1948. E. H. GOLDSMITH ET AL 2,457,543

OPTICAL SIGHTING DEVICE HAVING REFLECTOR MEANS FOR TRACKING MOVABLE OBJECTS 6 Sheets-Sheet 5 Filed. March 16, 1946 FIG. /0

ne so AZ/MUT TRANSMITTING I48 SELSYN Dec. 28, 1948. E. H. GOLDSMITH ET AL. 2,457,543

OPTICAL SIGHTING DEVICE HAVING REFLECTOR MEANS FOR TRACKING MOVABLE OBJECTS Filed March 16, 1946 6 Sheets-Sheet 6 .H. GOLDSMITH INVENTORSI J. m. scHAEFL-"R R. u TERRY A T TORNE V Patented Dec. 28, 1948 OPTICAL SIGHTING DEVICE HAVING RE- FLECTOR MEANS FOR TRACKING MOV- ABLE OBJECTS Elsworth H. Goldsmith, New York, N. Y., Roy V.

Terry, Maplewood, N. J and Jacob W. Schaefer, Philadelphia, Pa., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation oi New York Application March 1.6, 1946, Serial No. 654,980

This invention relates to optical sighting apparatus and more particularly to optical sighting apparatus usable as a means to detect and observe a moving target and keep track of the movements of the target.

The invention is applicable for use in combination with gun director apparatus and provides a means for detecting and observing a target and giving indications of the position and movements of the target.

In certain gun director apparatus devised and developed for training a gun to direct a projectile to a moving target the optical apparatus for detecting and observing the target is commonly called a tracker. The tracker in some cases is located remote from the gun and other parts of the gun director apparatus and it has been found necessary or advantageous in some cases to move the tracker to various locations.

In trackers of a type at present in use the major portion of the tracker is rotatably mounted on a support and is equipped with seats on which operators of the tracker sit while operating the tracker to detect and follow a target. When the major portion of the tracker is rotated in azimuth to detect a target the operators are carried around on the rotatab'e portion of the tracker and must makeso'me of their observations while in motion. The tracker is quite large and heavy and not readily transportable unless mounted on a suitable vehicle.

An object of the invention is to provide a relatively light weight and readily transportable optical sighting apparatus and in the operation of which the operators are not required to move around while making the required observations.

A feature of the invention resides in a head member of the optical sighting apparatus.

Another feature resides in light ray receiving and reflecting means provided In the optical sighting apparatus.

Another feature resides in an optical eye-piece device provided in the optical sighting apparatus.

In the drawings:

Fig. l is a view in perspective of the optical sighting apparatus embodying the invention;

Fig. 2 is an enlarged view, partly in section, of the head member and an upper portion of the supportin means for the head member;

Fig. 3 is an enlarged view, partly in section, of certain parts shown in Fig. 2 and taken on the line 33 in Fig. 2;

Fig. 4 is an enlarged view, partly in section, of the body of the optical sighting apparatus and parts contained in the body and looking down- 4 Claims. (Cl. 8 8- --72) 2 wardly in the body, this view being taken on the line 4-4 in Fig. 2;

Fig. 5 is an enlarged bottom plan view of a portion of the optical sighting apparatus taken on the line 5-5 in Fig. 3;

Fig. 6 is an enlarged side view, partly in section, of optical apparatus supported in the body and taken on the line 6-6 in Fig. 4;

Figs. 7 and 8 are enlarged views in section, of portions of the optical sighting apparatus;

Fig. 9 is an enlarged view, partly in section, of a portion of the optical sighting apparatus taken on line 9-9 in Fig. 7; and

Fig. 10 is a schematic illustration of some of the target detecting and observing means provided in the optical sighting apparatus and shows means for operating the target detecting and 0bserving means and Selsyn devices used in transmitting operations of the optical sighting apparatus to certain other parts, not shown, of gun director apparatus.

In tracker apparatus employed in detecting and observing an airplane in flight or some other moving target. means are provided to scan an area to search out a target. The scanning means must be movable in azimuth and elevation so that it may be trained on the target. The usual practice is to turn the major portion of the tracker in azimuth and tilt certain parts of the tracker to bring the target detecting and observing means in line with the target.

In the present invention it is only necessary to move a head member in azimuth and to tilt an image receiving means contained in the head member to train the tracker on a target.

The tracker embodying the present invention as shown in Fig. 1 comprises a support I l, a body I2 supported thereon and a head member I3 supported on the body I2.

The support II comprises a plurality of leg members I4 attached at their upper ends to a frame, not shown, but which is detachably connected to the body I2 to form a support for the body l2. The lower end of each leg member I4 extends into a Y fitting I5 equipped with a threaded rod I6 which extends downwardly through the Y fitting I5 and into a foot IT. The threaded portion of the rod i6 is in engagement with a correspondingly threaded portion in the Y fitting I5 and the threaded rod I6 may be turned to raise or lower the Y fitting I5 relative to the foot [1. By suitable adjustment of the threaded rods iii the support II may be adjusted to bring the body I2 to a required elevated or lowered position for convenient use by the operators of the tracker and to make the body stand level when the ground on which the tracker stands presents an uneven surface.

The body I2 is a casing in which certain parts of the tracker apparatus are housed and supported. As shown in Figs. 2 and 3 a top wall I8 of the body I2 is apertured at l9 to accommodate a flanged tube 20 supported in and extending downwardly from the head member I3 and into the body I2. The flanged tube 28 provides a passageway for light beams received in the head member I3 and directed from the head member i3 into the body i2. Surrounding the aperture I9 is a boss 2| with a recess 22 formed therein to provide a rest for a bearing support 23 in which inner and outer annular grooves are provided to support sets of ball bearings 24 and 25.

The head member I3 comprises a casing-type body 25 having a horizontal hood portion 21 extending upwardly from a dome portion 28, the lower end of the dome portion 28 being slightly elevated from the top wall I8 of the body I2 when the head member I3 is mounted in place. The hood portion 2'! extends only part way across the dome portion 28 and is open at one end 29 to accommodate a substantially L-shaped casing 38 in one end of which is supported a cover glass 3| which serves as a light receiving means for the head member I3. Trunnions 32 and 33 are provided on end portions of the casing 38 to engage in bearings 34 and 35 respectively, to support the casing 38 and permit the casing 38 to be rotated on a horizontal axis, the bearing 34 being mounted in a bracket 36 extending upwardly from the dome portion 28, the bearing 35 being mounted in an end wall 3'! of the hood portion 21 and the trunnion 33 being a projection on a flange 38 which is secured to an enlarged end portion 39 of an arm 48 extending from the casing 30 andlongitudinally of and within the hood portion 27. The open end 29 of the hood portion 21 is formed to provide an annular flange 4| to receive one end 42 of the body portion 43 of the casing 38 which is operable to rotate in the open end 29 of the hood portion 21. Surrounding the end portion 42 of the casing 30 and disposed between the flange 4| on the hood portion 21 and a flange 44 on the casing 38 is a Sylphon-type bellows 45, one end of the bellows 45 being secured to the flange 4| and the other end being equipped with a bearing ring 46 which is in frictional engagement with the flange 44. The bellows 45 is slightly compressed to develop spring pressure therein and serves to pre- Vent light rays and dust particles from entering the casing 30 and the hood portion 21 at the point where the casing 30 extends into the hood portion 27. A Sylphon-type bellows 41 is disposed within the space defined by the dome portion 28 of the head member l3 and the top I8 of the body I2 to stop light rays and dust particles coming through the space between the lower end of the dome portion 28 and the top I8 of the body l2. One end of the be lows 41 is secured to a ring 48 on the top I8 of the body l2 and the other end of the bellows 41 is equipped with a bearing ring 49 which is in frictional engagement with an annular boss 58 projecting from the undersurface of the dome portion 28.

Secured to and projecting from the flange 38 is a sector gear 5| which extends through an aperture 52 in the dome portion 28 and into engagement with a bevel gear 53 located within the dome portion 28. The casing 38 may be rotated on a horizontal axis by suitable operation of the bevel gear 53. When the bevel gear 53 is suitab y 1'0- tated the casing 38 is rotated on a horizontal axis.

The head I3 is rotatable as a whole on a vertical axis through operation of a gear 54 which is secured to the lower end of the flanged tube 20 and located within the body I2. The head i3 is rotated on a vertical axis to move the cover glass 3| in azimuth and the casing 38 is rotated on a horizontal axis to tilt the cover glass 3| for elevation. It is obvious therefore that the cover glass 3| may be moved as required to train the cover glass 3| on an airplane in flight or on some other moving target.

A mirror 55 is housed in the casing 38 to receive light rays reflected from the target on which the cover glass 3| is trained and to direct the light rays to a mirror 55. The mirror 55 is disposed "ngularly relative to the cover glass 3i and is supported at three spaced points. two of the points being engaged by spaced screws 51 and 58 which are adjustably mounted in screw supports 59 and 68 respectively supported on an inc'ined wall 8| on one end of the casing 30. The screws 51 and 58 project through apertures provided in the inclined wall 6| and each screw 51 and 58 as shown in Fig. 7 is provided with a bull and socket-type member 62 bearing against the rear surface of the mirror 55. In register with each screw 5'! and 58 and bearing against the front face of the mirror 55 is a spring-pressed ball 63 mounted in a holder 64 supported on the casing 38. At a remote point from the screws 5'! and 58 and as shown in Fig. 8 and engaging an insert in the outer edge of the mirror 55 is a ball 86 resting in a seated end of a plunger 8'! which is mounted in and projects through a portion of the casing 30. lly turning both screws 57 and 58 in the same direction the mirror 55 may be tilted within the casing 30, the screws 51 and 58 operating in one direction to move their engaged portions of the mirror away from the inclined wa l BI and against. the action of the spring-pressed balls 63 and pivotally movingthe mirror 55 on the ball 66, When the screws 5'! and 58 are rotated in another direction the spring-pressed balls 63 cause their engaged portion of the mirror 55 to move nearer the inclined wall 6|. Diilerential operations of the screws 51 and 58 will cause the mirror 55 to be turned on the pivot provided by the ball 58 and the insert 85. It will be apparent therefore, that since the mirror 55 may be tilted and rotated on its pivotal point of support the angular position of the mirror 55 relative to the cover glass 3| may be adjusted in two different ways. To maintain the mirror 55 pressed toward its pivotal point of support a spring-pressed rotatably supported pin 2I6 is mounted in the casing 30 to bear against a slotted edge 2|! of the mirror 55 at a point directly opposite from the pivota point of support of the mirror 55 provided by the ball 86.

Located within the space defined by the hood portion 21, as shown in Fig. 2, is the mirror 58 which is in position to receive an image of the target detected by the cover glass 3i and reflected by the mirror 55. The image is reflected by the mirror 55 to the mirror 56. The function of the mirror 56 is to reflect the image downwardly through the space defined by the flanged tubular member 20 and into the body I2 of the tracker. The mirror 58 is adjustably supported in a casing: 68 which has a tubular base portion 68 mounted on an apertured wall 18 of the dome portion 28 by means of the screws ll. Spaced side walls 12 and 13 of the casing 88 extend upwardly from the tubular base portion 69 and terminate in a pan portion 14 in which the mirror 56 is supported at spaced points by means of screws I5 and I6 and a ball IT and spring-pressed pins 18 in the same manner as the mirror 55 is supported in the casing 30.

Since the mirrors 55 and 56 are adiustably supported, they may be positioned to cooperatively direct an image of a target to a required point in the body I2 of the tracker.

As shown in Fig. 4, the body I2 contains a compartment I9, the walls of which cooperatively define a space 80 which is in register with the space defined by the flanged tubular member 20. Adjustably supported on brackets BI, 82 and 83 and located in the space 80 is a set 84 of prisms comprising the prisms 05, 86 and 87. Each prism is in register with an aperture provided in a wall of the compartment I9, the prism 85 being in register with an aperture provided in the wall 88, the prism 88 being in register with an aperture in the wall 89 and the prism 81 being in register with an aperture in the wall 90. The function of the set 84 of prisms is to receive light rays representing the image of the target picked up by the cover glass 3! and formed on the mirror 55 and reflected by the mirror 56 and direct the light rays representing the image into optical devices 9i, 92 and 93 supported in the body I2 and exterior of the compartment I9 and in register with the respective apertures 94, 95 and 96 formed in the walls 91, 98 and 99 respectively of the body I2. The optical devices 9i. 92 and 93 are equipped with the respective eyesight pieces I00, IM and I02 which are used by operators and attendants of the tracker in observing a target, the eyesight pieces I00, WI and I02 extending outwardly of the body I2. The optical device 9| receives light rays representing an image or the target from the prism 05 forms a virtual image of the target and directs the image to the eyesight piece I00. The optical device 92 receives light rays representing an image of the target I rom the prism 86 and forms a virtual image of the target and directs the image to the eyesight piece IIII, and the optical device 93 receives light rays representing an image of the target from the prism 81 and'forms a virtual image of the target and directs the image to the eyesight piece I02. The image of the target may therefore be observed simultaneously by three operators or attendants of the tracker.

Each optical device 9i, 92 and 93 is constructed along the same general lines and an understanding of the construction of one will be sufiicient for all. In Fig. 6 the construction of the optical device 9| is shown as comprising a tubular housing I03 having an apertured end wall I04 secured to the compartment I9 and so that the aperture in the end wall I04 is in register with one of the set 84 oi prisms, in this case the prism 05 being the one serving the optical device 9i. Directly in line with the prism 85 but located on the outer end of the housing I03 is an apertured flange I05 constructed to extend into an aperture I06 formed in the body I2 shown in Fig. l. Mounted on the flange I05 and arranged to extend through the aperture I05 and outwardly from the body I2 is the eyesight piece I having lens members I01 and I08 contained therein. as shown in Fig.

10. Located in the housing I03 and disposed between the eyesight piece I00 and the prism 35 is a rotor I09 comprising apertured end portions I I0 and I I I connected to a double inclined bridge portion II2 on which two mirrors H3 and I I4 are adjustably supported by means of screw members H5 and H6 and spring-pressed members II'I proViding in each case a three-point adjustable supporting system for the mirrors H3 and I I4. The mirror I I3 is downwardly inclined from a high point IIB on the bridge portion H2 and is directed toward a double lens system II9 supported in the apertured end portion I III of the rotor I09 in register with the prism 85. From light rays representing an image of the target and coming through the prism 05 the double lens system II9 forms a virtual image oi the target. The mirror H4 is downwardly inclined from the high point I I8 and is directed toward the eyesight piece I00. A mirror I is located at a position offset from the mirrors I i3 and I I4 and is adjustnbiy supported b means oi'serews I2i and springressed members I22 mounied in a bracket I23 secured at I24 to the housing: I03. The mirror I20 is positioned to receive an image from the mirror H3 and to reflect the image to the mirror IM which in turn will reflect the image into the eyesight piece I00. The rotor I09 is supported in bearings I25 and I '15, parts of which are mounted in the housing I03. A sector gear I2! is mounted on the rotor I09 to facilitate rotation of the rotor I09 in the housing I03.

The tracker may be operated to detect a target and follow the course oi a moving target by two persons, one being stationed on one side of the tracker and operating the azimuth liandwheel I28 shown in Figs. 1 and 10. The other operator is stationed on the side of the tracker opposite the position of the azimuth operator and operates the elevational handwheel I29 shown in Fig. 10. The tracker is provided with an azimuth dial I30 shown in Figs. 1 and 10 and an elevation dial I3I shown in Fig. 10 to show the relative settings of the elevation and azimuth mirrors, the body I2 being apertured at required points to accommodate certain shafts oi the manual controls and to permit observance of the dials. The tracker is also provided with an orientation handwhcel I32 shown in Fig. 10 to operate certain parts of the tracker to required relative initial positions. some of the paris being controlled through gear systems containing differential gear devices I33 and I34 shown in Fig. II). The tracker is also provided with Selsyn devices I35 and I36 which are employed as transmitting Selsyns to control certain parts of gun director apparatus located at some point or points remote from the tracker.

When the tracker is placed in required position for operation the threaded rods I6 are adjusted in the Y fittings I5 to get the head I3 in a level position, a spirit level device I3! mounted on the head I3 as shown in Fig. 1 being observed during the adjustment of the threaded rods I6.

To detect a target the head i3 is rotated on a vertical axis indicated by the. (lot-(lush line 2I0 and the casing 30 supported therein is rotated on a horizontal axis indicated by the dot-dash line 2I9 in Fig. 1 to scan an area being searched for the target. This may be done rather roughly at first and then more precisely later, as will be subsequently explained, or in a complete precision operation. In performing the precision operation one operator causes the head I3 to be rotated on the vertical axis 2I8 for azimuth positioning by manually turning the handwheel I28 which is known as the azimuth handwheel. This operator looks into the eyesight piece I00 to see an image of the target while the handwheel I28 is being operated. While this is being done a sec- 7 end operator causes the casing 30 in the head I3 to be rotated on the horizontal axis 2I9 for elevation positioning by manually turning the handwheel I29 which is known as the elevation handwheel. This second operator looks into the eyesight piece IOI to see an image of the target while the handwheel I29 is being operated. The head I3 and the casing 30 are rotated until the cover glass 3| is in register with the target. When the target is detected the operators of the handwheels I28 and I29 keep the cover glass 3I in line with the target by suitably operating the handwheels I28 and I29 and observing the images of the target visible by looking in the respective eyesight pieces I and NI. Another image of the target is visible also in-the eyesight piece I02 and this image may be observed by an attendant of the tracker known as a spotter. The eyesight piece I02 is known as the spotter eyesight piece. Images of the target are, therefore, visible at three positions in the tracker, namely, the azimuth position, the elevation position and the spotter position. As shown in Fig. and indicated by the dot-dash lines I38 and I39 in the figure light ray reflections from the target come through the cover glass 3| and are directed thereby to the mirror 55 which receives the light rays representing the image of the target and reflects the light rays representing the image to the mirror 56 which in turn reflects the light ray representing the image downwardly through the light passage provided by the flanged tubular member and into the body I2 of the tracker in which the prisms 85, 66 and B1 are contained. Each prism 85, 86 and 81 receives the light rays representing an image of the target and each prism refracts and directs the light rays representing an image of the target to a separate optical device equipped with an eyesight piece. As shown in Fig. 10 the prism 85 directs the light rays representing an image of the target into the optical device 9|, the prism 86 directs the light rays representing an image of the target into the optical device 92 and the prism 81, not

shown in Fig. 10 but shown in Fig. 4, directs the light rays representing an image of the target into the optical device 93.

Since the head I3 is rotatable on a vertical axis and the casing on a horizontal axis and the mirror 55 is turned for elevation and the mirrors 55 and 56 are turned in azimuth adjustment while reflecting the light rays representing the image to the prisms which are-stationary, the light ray images directed by the prisms into the optical devices 9|, 92 and 93 will appear to turn and produce an optical illusion that the target is turning. This illusion if carried to the eyesight pieces would give the operators incorrect impressions of the movement of the target. To correct the illusion and prevent it from being carried to the eyesight pieces I00, IOI and I02 the optical devices 9i, 92 and 93 are provided with the rotors I09 and means are provided to simultaneously rotate the rotors I09 in required manner to make the virtual images received in the eyesight pieces appear in true position.

Mounted in the body I2 of the tracker are systems of gears and shafts providing mechanical drives between the handwheels I28, I29 and I32 and rotatable parts of the head I3 and between a rotatable part of the head I3 and the rotors I09 of the optical devices 9|, 92 and 93. Mechanical drives are also provided to operate rotatable members in the Selsyns I35 and I36. The me chanical drives are shown schematically in Fig.

8 10 and will now be pointed out and explained in the order in which they operate.

In scanning an area to detect a target the head I3 of the tracker is rotated as a whole on a vertical axis for azimuth positioning of the cover glass Si by operation of the azimuth handwheel I28. During this operation the casing 30 is often rotated on a horizontal axis for elevation positioning of the cover glass 3I by operation of the elevation handwheel I29.

The azimuth handwheel I28 is in driving connection with the gear 54 through a mechanical drive I40 comprising sets of rotatable shafts and gears extending from the azimuth handwheel I28 to the gear 54 which is mounted on the flanged tubular member 20. The differential Hear device I33 is also included in the mechanical drive I40. The azimuth handwheel I28 is socu'red to a shaft I4I carrying a worm I42 engaging a wormwhcel I43 mounted on a shaft I44. When the azimuth handwheel I28 is rotated the following parts of the mechanical drive I40 are rotated shaft I4I, worm I42, wormwheei I43, shaft I44, bevel gear I45 mounted on shaft I44, bevel gear I46, shaft I41, gear I40, gear I49 and gear I50. If the orienting handwheell I32 is held against rotation the driving action will be continued to the head I3 by rotation of the following shaft I5I, bevel gear I52 carried on shaft I5I, bevel gear I53, shaft I54, pinion I55 on shaft I54, pinion I56, shaft I51 and pinion I58 engaging gear 54. Rotation of gear 54 causes rotation of the head I3 on a vertical axis. Gear I49 is secured to a shaft I59 which drives a rotor element of the Selsyn I35. The Selsyn I35 may be used as a transmitting Selsyn to control another Selsyn, not shown, but located at some point remote from the tracker and operable to control certain parts of gun director apparatus remote from the tracker.

The elevation handwheel I29 is in driving connection with a gear I60 through a mechanical drive I6I comprising sets of rotatable shafts and gears extending from the elevation handwheel I29 to the gear I60. The differential gear device I34 is also included in the mechanical drive I6I. The gear I60 is attached to and supports the bevel gear 53 which is in driving connection with the sector gear 5|. The elevation handwheel I29 is secured to a shaft I62 carrying a worm I63 engaging a wormwhcel I64 mounted on a shaft I65. When the elevation handwheel I29 is rotated the following parts of the mechanical drive I6I are rotated, shaft I62, worm I63, wormwheel I64, shaft I65, bevel gear I66 mounted on shaft I65, bevel gear I61, shaft I68, gear 169 and gear I10. If the differential device I34 is not free to idle,

the driving action will be continued to the casing 30 in the head I3 by rotation of the following, shaft I1I, bevel gear I12 carried on shaft I1I, bevel gear I13, shalt I14, pinion I15 on shaft I14, pinion I16, shaft I11 and pinion I18 secured to shaft I11 and in driving engagement with gear I60. Supported on and secured to the gear I60 is the bevel gear 53 which is in driving engagement with the sector gear 5i. When the sector gear Si is driven the casing 30 is rotated on a horizontal axis to point the cover glass 3I to a higher or lower place in the area being scanned. Gear I10 is in driving connection with a gear I19 secured to shaft I which is connected to the rotor element of the Selsyn I36. The Selsyn I36 may be used as a transmitting Selsyn to control another Selsyn, not shown, but located at some point remote from the tracker and forming part of a gun director apparatus located remote from the tracker.

The difierential gear devices I33 and I34 are epicyclic differential gear devices in which the two end bevel gears are free to rotate on the shaft and the side bevel gears are rotatably supported on arms extending from a central cross fitting IOI which is secured to the shaft. When one of the end bevel gears in the differential device is held or retarded against rotation the side bevel gears in the differential device walk around on the held or retarded end bevel gear and cause rotation of the shaft in the differential gear device.

A cross-connecting gear drive I82 is provided to control the differential gear device I34 from the gear drive I40 to nullify any driving effects rotation of the head I3 as a whole on a vertical axis might otherwise have on the casing 30 and such as might come by reason of the engagement of the sector gear I with the bevel gear 53. The cross-connecting gear drive I82 comprises a bevel gear I83 secured to the shaft I54, a bevel gear I84 in mesh with gear I83 and secured to a shaft I85, a. pinion I86 secured to shaft I85 and engaging a pinion I87 secured to shaft I08 and a pinion I89 secured to shaft I88 and in mesh with a pinion I90 freely rotatable on the shaft Ill of the differential gear device I34. The pinion I90 is secured to the end bevel gear I9I of the differential gear device I34. When the head I3 is turned as a whole on the vertical axisand the sector gear 5i operates to tend to drive the gear 53 the cross-connecting gear drive I82 operates on the differential gear device I34 to make the differential gear device I34 counteract any driving effects of the sector gear 5I on the gear 53 and through the mechanical drive I6I.

The orienting handwheel I32 may be held or locked while the azimuth handwheel I28 is turned. In this case the end gear I92 in the differential gear device I33 will be held and the side gears I93 and I94 will walk around on the end gear I92 and rotate the cross-fitting I95 which is secured to the shaft I5I.

As above-mentioned, the optical devices SI, 92 and 93 are provided with rotors I09 and the rotors I09 are rotated at one-half the speed of rotation of the combined speeds of easing type body 26 and casing No. 30 in order that virtual images coming into the eyesight pieces I00, WI and I02 will appear in true position. As shown in Fig. 10, a mechanical drive I96 is provided to drive the rotors I09 in the optical devices 9|, 92 and 93. The optical device 93 is not shown in Fig. since this optical device is disclosed at a QO-degrce angle from the positions of the, optical devices 9| and 92 shown in the figure. The mechanical drive I96 comprises a pinion I97 in mesh with the gear I60 and secured to a shaft I90, a bevel gear I99 secured to the shaft I98 and engaging a bevel gear 200 secured to a shaft I, a pinion 202 secured to the shaft 20I and in mesh with a gear 203 secured to a shaft 204. Secured to one end of the shaft 204 is a gear 205 in mesh with the sector gear I2! on the rotor I09 of the optical device 9i. Secured to the other end of the shaft 294 is a bevel gear 206 in mesh with a bevel gear 20?, secured to a shaft 208. The bevel gear 20'! is in mesh with a gear 209 secured to a shaft 2 I 0 on one end of which is secured a gear 2| I in mesh with the sector gear I21 on the rotor I09 of the optical device 92. Secured also to the shaft 208 is a gear 2 I 2 to drive a shaft, not shown, but leading to and forming a driving means for gfiillClS outwardly thereof.

the rotor I09 of the optical device 93. When the head I3 is being operated and the gear I60 is turning while the cover glass 3I is being pointed at a target, the mechanical drive I96 is operating to rotate the rotors I09 in the optical devices SI, 92 and 93. The mechanical drive I is designed to make the rotors I09 in the optical devices SI, 92 and 93 operate in required manner to make the virtual images of the target appearing in the eyesight pieces I00, WI and I02 appear in correct position compared with the target, the rotors I09 being rotated in directions reverse from the directions of rotation of the images coming to the prisms 05, 86 and 81, the rotations of which are caused by rotations of the mirrors in the head I3 relative to the prisms 85, 86 and 87.

A bracket 2I3 is mounted on the casing 30 and The bracket 2I3 supports an infinity sight 2I4 through which an mtendant of the tracker may sight a target and check with the operators of the tracker in pointing the cover glass 3I directly in line with the target. The optical devices BI, 92 and 93 are provided with means to show appropriate hair lines in the fields viewable in the eyesight pieces I00, IOI and I02 to compare with the images of ihe target, the optical device 9| showing a vertical hair line, the optical device 92 showing a horizontal hair line and the optical device 93 showing cross hair lines and a calibrated scale. The infinity sight 2 I4 may have a lens system therein producing an optical eilcct of showing concentric colored rings extending around the center of the viewed field to enable the observer to roughly center a target in the field of view of the operators and attendants who are viewing the target through the eyesight pieces I00, IOI and I02.

The attendant of the infinity sight 2I4 can operate the head member I3 to scan an area and detect a target. In this case, the attendant of the infinity sight 2I4 grasps the bracket 2I3 and turns the head member I3 on a vertical axis and rotates the casing 30 on a horizontal axis by manually moving the bracket 2I3 in a suitable manner to point the infinity sight 2I4 to the area to be scanned and finally bring the infinity sight 2I4 in line'with the target. The attendant oi the infinity sight 2I4 may, therefore, slow the head member I3 in relatively quick movements to scan an area and detect a target and roughly bring the cover glass (H in line with the target, the attendant oi the infinity sight 2I4 observ ing the area being scanned by looking through the infinity sight 2I4 while he is operating the head member I3. When the attendant of the infinity sight 2I4 has brought the cover glass 3| in line with the target he can discontinue his operation of the head member I3 and let the operation of the azimuth and elevation handwheels take control. Clutch operating handles 2I5 are provided in the tracker to control clutches, not shown, but contained within the body I2 and located in the gear driving systems. The clutch operating handles 2I5 may be operated to release some parts of thc gear driving systems from operation to permit relatively easy slewing of the head member I3.

The tracker embodying the present invention is readily transportable since it is relatively light in weight and small in size. The structure is also of considerable advantage since only the head portion need be exposed while all other portions may be set below ground level or otherwise protected from enemy observation or assault. The

head might be made to extend a greater distance above the body than as shown in the figures to enable lower placement of the major portion of the tracker in an excavation or protective vault.

What is claimed is:

1. An optical sighting apparatus comprising a box-like body, apertured top and side walls in said body, a dome-like head rotatably supported on said body and rotatable on a vertical axis with respect to said body, an L-shaped casing supported in said head and rotatable on a horizontal axis with respect to said head, means for rotating said head on the vertical axis, and means for rotating said L-shaped casing on the horizontal axis, a light reflecting device in said L-shaped casing to receive light reflections from outside said L-shaped casing and to transmit the light reflections into said head, a light reflecting device in said head arranged to receive light reflections from the light reflecting device in said L- shaped casing, and to transmit the light reflections into said body, a set of light reflecting devices in said body to receive the reflections transmitted into said body by way of said head, each light reflecting device in said set being arranged to transmit light reflections in a direction different from the direction of transmission by other light reflecting devices in said set, and an optical eye-piece individual to each reflecting device in said set and supported in spaced relation in said body and extending through an apertured side wall in said body, said optical sighting apparatus providing a means whereby a plurality of persons operating the optical sighting apparatus may simultaneously see an image of a distant object on which the optical sighting apparatus is trained.

2, An optical sighting apparatus comprising a box-like body, apertured side walls in said body, a dome-like head supported on said body and retatable on a vertical axis with respect to said body, an L-shaped casing supported in said head and rotatable on a horizontal axis with respect to said head, means to rotate said head on the vertical axis, means to rotate said L-shaped casing .on the horizontal axis, a light reflecting device supported in said L-shaped casing to receive light reflections from a distant object and to reflect said light reflections into said head,

a light reflecting device supported in said head to receive the light reflections and to transmit the light reflections into said body, a set of prisms supported in said body to receive the light reflections transmitted by said light reflecting devices, said set of prisms operating to transmit the light reflections in a plurality of different directions, and toward the apertured side walls or said body, and optical eye-pieces supported in the apertured side walls of said body and extending to the outside of said body and arranged to receive light reflections from said set of prisms, said optical sighting apparatus providing a means whereby a plurality of persons operating the optical sighting apparatus and looking into said optical eye-pieces may see an image of a distant object when the optical sighting apparatus is trained on the distant object and light my reflections are coming into said head from the distant object.

3. An optical sighting apparatus through which a distant object may be sighted and observed comprising a box-1ike body, apertured top and side walls in said body, a dome-like head rotatable on a vertical axis with respect to said body and supported on top of said body, an elbowtype casing rotatable on a horizontal axis with respect to said head and supported in said head, a portion of said elbow-type casing extending from said head, a light receiving and reflecting device supported in said elbow-type casing to receive light rays, and to reflect the light rays into said head, a light receiving and reflecting device supported in said head to transmit the light rays into said body, a set of spaced and angularly disposed light reflecting devices in said body, each of the light reflecting devices in said set operating to reflect the light rays toward a separate opening in a side wall of said body, an optical eye-piece for each light reflecting device in 'said set and mounted in an apertured side wall oi said body and in register with said set of light reflecting devices, a rotor in each optical eye-piece, reflectors on said rotor and a stationary reflector in spaced relation with said reflectors, means to rotate said head on its vertical axis, means to rotate said elbow-type casing on its horizontal axis and means to automatically rotate the rotors in the optical eye-pieces when said dome-like head is operated.

4. An optical sighting apparatus through which a distant object may be sighted and observed comprising in combination, a box-like body, apertured top and side walls in said body. a dome-like head rotatable on a vertical axis with respect to said body and supported on top of said body, an elbow-like casing rotatable on a horizontal axis with respect to said head and supported in and extending from said head, means in said elbow-type casing to receive light rays reflected from the distant object and to reflect the light rays into said head, means in said head 40 to reflect the light rays into said body, optical eye-pieces mounted in apertured side walls in said body and extending to the outside of said body, means mounted in said body to reflect the light rays into said optical eye-pieces, means to rotate said head on its vertical axis, means to rotate said elbow-like casing on its horizontal axis, a bellows forming a light ray excluding wall between a portion of said body and a portion of said head, and a bellows forming a light ray excluding wall between a portion of said head and a portion of said casing.

ELSWORTH H. GOLDSMITH.

ROY V. TERRY.

JACOB W. SCHAEF'ER.

REFERENCES CITED The following references are of record in the flle oi this patent:

UNITED STATES PATENTS Number 

